Trunked communications systems are well known in both the telephone and mobile radio communications art. In such systems, a plurality of communications units share a limited number of communication resources. Examples of such resources include frequency division multiplex (FDM) frequency pairs, time division multiplex (TDM) time slots, etc. Generally, these communication resources are assigned to communications units (e.g., mobile radios, portable radios, consoles, etc.) by a central resource controller. The resource controller might be implemented as a base control station having central or distributed control logic. In either case, the control base station houses the necessary hardware for communicating with the communication units in its coverage area. This hardware includes transmit circuitry as well as receive circuitry. The transmit path typically includes filters, combiners, transmission lines, and an antenna. The receive path typically includes an antenna, a preamplifier stage, transmission lines, multi-couplers, and filters.
Each of the components in the transmit and receive paths are subject to degradation in performance (e.g., due to aging, thermal stress, etc.), and even complete failure. Of course, when component performance degrades, the integrity of the entire communication system is compromised. In the case of component failure, the system may be inoperable for the time it takes to detect, and repair, the failed circuitry. While complete communication system failure is uncommon, component degradation and hardware failure must be considered when designing for a reliable system. Further, except where there is hardware redundancy, the requirement to repair or replace a failed component exists. Accordingly, the detection of failed or degraded components becomes critical to the overall system performance. That is, the time in which it takes to detect a problem becomes a limiting factor for the integrity of the entire system.
In today's trunked communications systems, the aforementioned components are regularly checked (e.g., by service technicians who perform off-line testing of the hardware using external test equipment. This approach has two problems associated with it. First, the integrity of the system is likely to be only as sound as the maintenance schedule for the system. Without a proper maintenance schedule, system testing is either cost prohibitive, or unreliable (i.e., checked more often than necessary, or checked too infrequently to achieve the required system performance results). Second, the systems must be taken off-line in order to perform the maintenance testing. Of course, this results in reduced system efficiency, reduced revenues, and dissatisfied users.
Accordingly, a hardware testing scheme which could be automatically, and timely, performed would be an improvement over the prior art. Further, a testing scheme which could be performed while the system is on-line would greatly enhance the resulting efficiency of such a scheme.